Research On Coordination Region Of Hypersonic Flight Vehicle Based On Aerodynamic Coupling

Hypersonic flight vehicle is a new strategic flight vehicle in today’s era.It has many advantages such as wide flight range,good economic benefit and strong penetration ability.However,in hypersonic flight,due to the complexity of its flight environment,strong nonlinear characteristics will be caused,so that the aerodynamic moments of the pitch channel,yaw channel and roll channel of hypersonic flight vehicle will interact and influence each other,which is called aerodynamic coupling.The existence of aerodynamic coupling is very unfavorable to the coordinated flight of hypersonic flight vehicle,which increases the difficulty of flight control.If allowed to accumulate,it will even affect flight safety.Therefore,it is necessary to study aerodynamic coupling and take corresponding coordination control to constrain the flight vehicle within a certain coordination area,which is conducive to ensuring good performance of hypersonic flight vehicle in flight.In this paper,from the perspective of aerodynamic coupling,the coordination integration of hypersonic flight vehicle is studied to obtain the flight coordination region of the flight vehicle.The main research contents of this paper are given as follows:Firstly,based on the test report and aerodynamic data of the hypersonic flight vehicle issued by NASA,a relatively ideal assumption is made for the flight conditions of the flight vehicle,and a corresponding aerodynamic mathematical model is established.Based on this model,an equivalent deflection strategy design is performed on the aerodynamic rudder surface.The aerodynamic couplings between three attitude channels of hypersonic vehicle,which mainly include: aerodynamic coupling caused by attitude angular rate and aerodynamic coupling caused by equivalent rudder deflection angle,are qualitatively analyzed.Secondly,the aerodynamic couplings between three attitude channels of hypersonic vehicle are quantitatively analyzed.According to the coupling analysis method of dynamic equation,the corresponding aerodynamic coupling degree matrices are obtained,and on this basis,the main diagonal processing of coupling degree matrices are carried out,and the concept of negligible/nonnegligible aerodynamic coupling is put forward.Then,the corresponding coupling controller is designed,which can effectively change the control strategy according to the change of aerodynamic couplings during the flight,so as to realize the coordinated processing of hypersonic flight vehicle and ensure the good flight quality of hypersonic flight vehicle.Then,the attitude system balance surface of hypersonic flight vehicle is obtained by using the continuous algorithm,which is taken as the target set.In this case,the safe flight of hypersonic vehicle can be guaranteed the state points in the backward reachable set,but it is not completely coordinated.The negligible/non-negligible aerodynamic coupling boundary is taken as the constraint to achieve the screening of the backward reachable set,and the state points with non-negligible aerodynamic coupling are removed to obtain the attitude flight safe region of the initial hypersonic vehicle.Then the attitude coordination controller designed above is used to deal with the non-negligible aerodynamic coupling,and the attitude flight coordination region after the coordination is obtained.Flying in this area can ensure the coordination between attitude channels of hypersonic flight vehicle.Finally,based on the longitudinal model of the hypersonic flight vehicle,the qualitative analysis of the aerodynamic coupling between its variables is performed first,and then the dynamic coupling analysis method is used for quantitative coupling analysis to obtain the accurate coupling relationship in the longitudinal system.The longitudinal safe area of the hypersonic flight vehicle is obtained by using continuous algorithm and backward reachable set idea.The longitudinal coordinated controller is designed based on the boundary of negligible/non-negligible coupling to realize the processing of longitudinal aerodynamic coupling and the longitudinal flight coordination region after the coordination is obtained.